Infiniti rolls out its 2011 M sedan

The redesigned 2011 Infiniti M56 will have a starting price of $57,550. It’s powered by a 5.6-liter engine rated at 420 horsepower.

SAN DIEGO, Calif. — The redesigned 2011 Infiniti M sport sedan is now on its way to dealers with a starting price of $46,250 (plus $865 freight) for the M37 (V-6) version, and $57,550 for the M56 (V-8) model.

The all-wheel-drive models are the M37x, with a base price of $48,400, and the M56x, at $60,050.

Despite numerous upgrades and lots of new standard features, base prices of the rear- and all-wheel-drive V-6 models are up just $450 from the 2010 versions. The V-8 rear-drive model’s price rises $2,050, but the all-wheel-drive version is up just $750 — mostly because it no longer carries the federal gas-guzzler tax that was figured into the 2010 price.

Infiniti showed off the new models to automotive journalists recently during a ride-and-drive event in San Diego, with test routes mapped out through the mountain roads southeast of the city and starting from a base at the U.S. Olympic Training Center.

The M37, with its 330-horsepower, 3.7-liter engine, had plenty of zip, along with handling worthy of the “sport sedan” designation.

But there was no escaping the fact that the V-8 model, with 90 more horses under the hood, was the most fun of the two. It’s powered by a 5.6-liter engine rated at 420 horsepower and 417 foot-pounds of torque.

Surprisingly, Infiniti was able to increase fuel economy for all models even though power was boosted significantly from 2010.

EPA ratings for the M37 are now 18 mpg city/26 highway, up from 17/25 for 2010; the M37x is rated at 17/24, up from 16/22 for 2010.

With the new 5.6-liter V-8 engine, which replaced the 2010 model’s 4.5-liter, fuel economy with rear drive is now 16 city/25 highway, up from 16/21 for 2010. With all-wheel drive, the ratings are 16/23, up from 14/20 for 2010 (which was bad enough to make the M45, the predecessor of the M56, subject to the guzzler tax).

The M, introduced originally in 2004 as a sedan priced between the entry level G35 and the high-end Q45, was last redone in 2006 and became the top Infiniti model when the Q was discontinued.

The 2010 models are called the M35 and M45; the new M37 and M56 names reflect the 3.7- and 5.6-liter displacements of the new engines.

Positioned from the start as driver’s vehicles meant to be the Japanese equivalent of Germany’s BMWs, Infiniti vehicles are always fun to drive, and these new M models take that fun to a higher level, making them worthy of the brand’s promise of “Inspired Performance.”

The M37 comes with its own version of the fantastic 3.7-liter V-6 that is found in a variety of Nissan/Infiniti products, including the 2010 Nissan 370Z sports car and the G37 sedan, coupe and convertible.

Both M models come with a seven-speed automatic transmission, and the optional Infiniti “intelligent” all-wheel drive is an added bonus for sporty handling on any road surface, wet or dry.

The M gets a complete exterior redesign with what Infiniti calls “evocative new styling with a low front end and deeply sculpted fenders.”

Also included are a variety of new high-tech systems, something that began with the second generation of this vehicle.

Among the standard or available features are Active Noise Control, the Forest Air climate-control system, the latest version of the Infiniti selectable drive-mode control, Active Trace Control, Eco Pedal and the enhanced Infiniti hard-drive navigation system, the company said.

Also available is the Infiniti Blind Spot Intervention System, designed to alert the driver if another vehicle is detected in the adjacent lane and to help nudge the car back toward the center of its own lane if it begins moving toward the vehicle in the other lane.

Infiniti said in San Diego that it would introduce the next generation of its QX56 full-size sport utility vehicle at the New York auto show in April. That also will be a 2011 model, and it will go on sale later this year.

Production of the M models and the new QX will be in Japan; the current QX is assembled in Canton, Miss.